I F19 am in a relationship with someone F20 who's really sensitive to any form of rejecting, what can i do to make her feel like she's accepted?

I've fallen into the habit of over-reassuring her and we both notice that isn't doing much. I'm considered very easy-going and I can accept that in a relationship we will annoy and get mad at each other. But anytime she prompts me to say how I really feel about a situation, I can feel her getting upset when the answer is slightly negative but we both said I never complain much about what happens but she finds herself complaining a lot more. I tell her "Well, we both process things differently." but it's starting to get to the point where I feel like I am being restricted emotionally or might accidentally feed into her rituals.